We measured in a continuous manner using tomography technique the dispersion state of suspension polymer products in a stirred-type reactor. We found quantitatively the relationship between the quality of reaction state in a polymerization proceeding and the operational conditions such as impeller rotational speeds and concentrations of dispersion reagents. We got, thereby, the useful information in order to stably perform suspension polymerization in the reactor and further to finely control the reaction to obtain the polymer products of the better quality.